Quadrupole mass spectrometer apparatus, for use in the sensing of the presence and quantity of chemicals in a gaseous ambient, would include as a main element, a quadrupole mass filter structural assembly capable of atomic selection based on atomic particle mass, together with means for introducing ionized ambient gas into the quadrupole mass filter, means for detecting specific ions in the ionized gas and means for detecting quantity and quality attributes of those selected ions.
In operation; to the quadrupole mass spectrometer device, there is supplied to individual diagonally positioned pairs of rod shaped conductor members, combined, direct current (DC) levels and phased radio frequency (RF) signals; such that, for a fixed value of RF and DC voltages, input ion energy, conductor dimensions and frequency: there is produced a hyperbolic field. The hyperbolic field affects the ability of certain ions, having a specific ratio of charge to mass, that in turn is identifiable with certain chemicals, to be diverted for processing in a detection capability.
The technology of quadrupole mass spectrometry is being extensively studied in the art. Examples of publications are Peter H. Dawson, Quadruple Mass Spectroscopy and its Applications, (Elsevier, N.Y. (1976), pp 9-11), and R. A. Syms et al, in IEEE Transactions on Electron Devices 45, 2304(1998).
In the translation of the quadrupole mass spectrometry technology into useful devices and apparatus there will be encountered interrelated dimensions within an operating background pressure that in turn is in an assembly of rod shaped members in a spatial volume wherein fields can provide conditions for chemical separation. To the quadrupole mass spectrometer device, there is supplied to individual diagonally positioned pairs of the rod members, combined, direct current (DC) levels and phased radiofrequency (RF) signals; such that, for a fixed value of RF and DC voltages, input ion energy, conductor dimensions and frequency: there is produced a hyperbolic field in the spatial volume. The hyperbolic field affects the ability of certain ions, arriving through the ion path opening, that have a specific ratio of charge to mass, that in turn is identifiable with certain chemicals, to traverse the spatial volume and be processed in a detection capability beyond the ion path exit.
The quadrupole mass spectrometer device is sensitive to dimensions and operating pressure. The work of Boomselleck and Ferran, reported in Am. Soc. For Mass. Spec. 12,633 (2001) advances highly useful factors including that maximum operating pressure is inversely proportional to the length dimension of the mass filter, and, that sensitivity is influenced by the “r” and “L” dimensions of the mass filter. The dimensions “r”, “L”, and “D” are labelled in FIG. 2.
As the art has developed, a promising design for the mass filter has evolved; wherein between upper and lower plane surfaces there is an enclosed spatial volume within which there is located a configuration of four parallel, equidistant as around a bolt circle, rod shaped conductor members, each of which extends between the upper and lower plane surfaces. The promising mass filter design further provides an ion path opening and exit, positioned, centered into and centered exiting from the upper and lower planes within the spatial volume containing the rod shaped conductor member configuration. The rod configuration is a building block in the fabrication of the mass filter. This building block, in turn, permits the fabrication capabilities of the semiconductor industry in producing large area arrays.
At this point in the art however there is a significant technical hurdle to be overcome because the length dimension of the mass filter will have to be very long in relation to the horizontal dimensions in other words the mass filter will have to have a large relative length to horizontal aspect ratio.